Process for the production of 1-ketocyclo-octyl-2-acetic acid



PROCESS FOR THE PRODUCTION or l-KETO- *CYCLO-OCTYL-Z-ACETIC ACID Otto Schlichting and Guenter Scheuerer, Ludwigshafen (Rhine), Germany, assignors to Badische Anilin- & Soda-Fabrik Aktiengesellschaft, Ludwigshafen (Rhine), Rhineland-Pfalz, Germany Application September 13, 1956 Serial No. 609,520

4 Claims. (Cl. 260-464) No Drawing.

. reacting a tertiary 2-aminomethylcyclo-octanone-(l), 1n

the form of its salts or its quaternization products, with an alkali cyanide and saponifying the resultant Z-(cyanomethyl) -cyclo-octanone- 1 The course of the reaction, when using Z-dimethylaminomethylcyclo-octanone-(2)-iodomethylate and sodium cyanide as initial materials, may be reproduced as follows:

CHr-C 2 1120 C=O +NaCN H2O CHCHz-N(CH3)3 I CHz-CHz GET-CH2 H2O C=O H2O l i N(CH3)3 NaI H2O /CH-CH2CN CH2CH:

GET-CH2 H2? (3:0 H2C\ CH-CHz-COOH CHT-C 2 The tertiary Z-aminomethylcyclo-octanone-(1) can readily be prepared according to the principle of the so-called Mannich reaction by reaction of cyclo-octanone with formaldehyde and secondary amines, such as dimethylamine, diethylamine, methylethylamine, pyrrolidine, piperidine or morpholine. From these tertiary amines, the salts or quaternization products serving as initial materials for the present invention are obtained in known manner for example by reaction with hydrogen chloride, bromide or iodide or with methyl or ethyl iodide or bromide, with dimethyl sulfate or para-toluene sulfonic acid ethyl ester.

The reaction of the salts or quaternization products of the Mannich bases of cyclo-octanone with alkali cyanides is preferably carried out in aqueous or aqueousalcoholic solution. The formation of the nitrile is carried out at a temperature at from about 20 up to 100 C., and is promoted by heating, for example, at 50 to 80 C., and by the use of an excess of sodium or potassium cyanide. The amine thereby set free in accordance with the above reaction scheme may be collected, when it is volatile under the reaction conditions, in dilute acid; in other cases it is recovered for example by fractional distillation.

The Z-(cyanomethyl)-cyclo-octanone-(1) obtained is a water-insoluble, colorless, liquid smelling of bitter almonds, which can be purified by distillation. It exhibits properties typical for a gamma-ketonitrile. It forms, for instance, a semicarbazone and can be saponified to the corresponding gamma-keto carboxylic acid.

States Pate "ice The saponification of the nitrile is preferably effected by heating with aqueous caustic alkali solution. From the resultant solution of its alkali salt, the l-ketocyclooctyl-2-acetic acid is obtained by neutralization, for example with hydrochloric or sulfuric acid.

The new gamma-keto acid thus obtained and its watersoluble salts have cholagogic action which is shown to be considerably greater than that of dehydrocholic acid in experiments on guinea pigs.

The following examples will further illustrate this invention but the invention is not restricted to these examples. The parts specified are parts by weight.

Example 1 146 parts of 2-dimethylaminomethylcyclo-octanone- (l)-iodomethylate (melting point 182 to 184 C., prepared by reaction of 91 parts of Z-dimethylaminomethylcyclo-octanone-(l) with 106 parts of methyl iodide in ethyl acetate solution) are introduced into a solution of 66 parts of sodium cyanide in 1,320 parts of water while stirring. The originally clear solution is heated for about minutes at 65 to 70 C., trimethylamine thereby escaping and 2-cyanomethylcyclo-octanone-(l) separating as an oil. It is allowed to cool, the oil is separated, the aqueous layer extracted with ether, the ether extract united with the oil, dried with sodium sulfate and the ether evaporated. The residue yields by distillation 68 parts of 2-cyanomethyl-cyclo-octanone-(1) of the boiling point 106 to 107 C., at a pressure of 0.3 Torr. The ketonitrile may be characterized by its semicarbazone which melts at 127 to 128 C.

68 parts of 2-cyanomethylcyclo-octanone-(l) are boiled under reflux with a solution of parts of potassium hydroxide in 460 parts of water for 7 to 8 hours. After cooling, any unsaponified material is removed by extraction with ether, whereupon hydrochloric acid is added to the aqueous-alkaline layer until it gives an acid reaction to congo. The free l-keto-cyclo-octyl-2-acetic acid in general separates at first as an oil. The aqueous layer is extracted with ether, the ether extract united with the oil, dried over sodium sulfate and the ether evaporated. 67 parts of 1-ketocyclo-octyl-2-acetic acid are obtained which after recrystallization from cyclohexane melts at 71 to 72 C. Its phenyl hydrazone has the melting point 109 to 110 C. (with decomposition).

Example 2 97 parts of 2-trimethylammonium-methylcyclo-octanone(1)-methyl sulfate (melting point 99 C., prepared by reaction of 73 parts of 2-dimethylaminomethylcyclooctanone-(l) with 252 parts of dimethyl sulfate in dry tetrahydrofurane with the addition of small amounts of glacial acetic acid at 10 to 15 C.) are reacted with a solution of 48 parts of sodium cyanide in 950 parts of water as in Example 1, there are obtained 36 parts of 2-cyanomethylcyclo-octanone-(1) and from this 36 parts of 1-ketocyclo-octyl-2-acetic acid.

Example 3 44 parts of 2-dimethylaminomethylcyclo-octanone-(1)- hydrochloride (melting point 138 to 139 C. with decomposition, prepared by leading dry hydrogen chloride into a solution of 40 parts of 2-dimethylaminomethylcyclooctanone-(l) in parts of absolute ethanol while cooling and precipitation with absolute ether) are reacted with a solution of 30 parts of sodium cyanide in 600 parts of water as in Example 1. There are obtained 18 parts of 1-ketocyclo-octyl-2-acetic acid.

Example 4 108 parts of 2-piperidinomethylcyclo-octanone-(l)- iodomethylate (melting point 126 to 128 C., prepared Z-acetic acid which comprises reacting a compound of the general formula in which R is a member of the class consisting of hydrogen and lower alkyl groups, R'R"N represents the radical of a secondary amine selected from the class conasisting of lower dialkyl amines, pyrrolidine, piperidine about 100 C. with an aqueous solution of an alkali 5 metal cyanide and saponifymg the 2- (cyanomethyl-)cyclooctanone-( 1) thus obtained by means of aqueous caustic alkali.

4. The water-soluble salts of l-ketocyclooctyl-Z-acetic acid.

References Cited in the file of this patent UNITED STATES PATENTS 2,068,586 Ziegler Jan. 19, 1937 2,773,087 Stork Dec. 4, 1956 FOREIGN PATENTS 934,103 Germany Oct. 13, 1955 OTHER REFERENCES Snyder t al.: J.A.C.-S., vol. 70, 1703-05 (1948) Kuehl, In, et al.: Chem. Abst., vol. 45, 332849 (1951). Blicke et a1.: J.A.C.S., vol. 75, 5418 (1953). 

3. A PROCESS FOR THE PRODUCTION OF 1-KETOCYCLOOCTYL2-ACETIC ACID WHICH COMPRISES REACTING A COMPOUND OF THE GENERAL FORMULA 